Effects Of Soybean And Maize Rotation And Fertilization On Soil Organic Carbon Components And Microbial Diversity

The purpose of this experiment was to clarify the changes of soil organic carbon components and microbial community structure before and after soybean-maize rotation,soybean continuous cropping and maize continuous cropping combined with fertilization,and to explore the relationship among soil nutrients,organic carbon components and soil microbial community diversity.The results of this experiment are as follows:(1)Rational rotation can improve nutrient content,such as total nitrogen,available nitrogen and available phosphorus,which can promote the absorption of available potassium by plants also.Soybean-maize rotation increased soil total nitrogen and content by 0.01-0.08 g/kg and that increased soil available nitrogen content by 20%-41%.Crop rotation combined with organic fertilizer could promote plant uptake of available potassium in 5oil.Soybean-maize rotation with organic fertilizer and soybean continuous cropping reduced available potassium by 31%and 33%,respectively.(2)Rotation can increase soil organic carbon content and maintain the original easily oxidized organic carbon in soil.Soybean and maize rotation could effectively reduce the decomposition rate of organic carbon,but the total organic carbon of non-fertilization treatment decreased dramatically by 16.8%.After rotation,the content of soil easily oxidized organic carbon changed little.Without fertilization,the content of soil easily oxidized organic carbon decreased by 0.10-0.12g/kg in maize continuous cropping and soybean-maize rotation treatments.The light fraction organic carbon content of maize continuous cropping and soybean-maize rotation decreased by 9.4%-28.6%under organic fertilizer application,while the light fraction organic carbon content of soybean continuous cropping increased by 32.8%.(3)A total of 17 phyla,62 classes,93 orders,170 families and 293 genera were detected in this test.Rotation ehanged soil bacterial diversity.The dominant bacteria in soil were Proteobacteria,Bacteroides,Acidobacteria,Actinobacteria and Firmicutes,but there were significant differences in species abundance and microbial community structure between treatments.It was found that fertilization had a significant effect on bacterial community structure,especially on maize continuous cropping.(4)A total of 8 phyla,19 classes,36 orders,54 families and 59 genera were detected in the research.The dominant phylum of fungi in soil were Ascomycota,Mortierellomycota,Basidiomycota,and Unclassified represented more than 95%of all the fungi.The dominant species were basically the same,but the species abundance was significantly different.It was found that Ascomycota in soil could promote the synthesis of heavy fraction organic carbon.Rotation effectively reduced the species abundance of Basidiomycota and the incidence of soil diseases,and had a significant impact on the structure of microbial comnunities.